1. Field of the Invention
The present invention pertains to a device capable of preventing counting errors with regard to the number of rotations of a driving device or a driving source used to drive a movable member such as a photo-taking optical system or X-Y table, as well as to an apparatus equipped with said device.
2. Description of the Prior Art
In connection with an apparatus having a movable member, i.e., in connection with the focusing or zooming of the photo-taking optical system in a camera lens mount, for example, when the lens units are driven, the number of rotations of the drive motor, which is the drive source for said lens units, is conventionally counted by means of pulse counting using a construction in which blades that rotate together with the drive motor pass through a gap of a photo-interrupter. By means of this counting, the amount of drive performed by the drive motor may be confirmed and the lens units may be driven to their desired positions.
However, in the construction described above, there is a possibility of an error occurring in the counting of the number of rotations of the drive motor when reactive reverse rotation occurs due to the elasticity, etc., of the components comprising the reduction mechanism located in the path used to transmit the driving force of the drive motor to a driven member.